User equipment (ue) and core network for managing network slice congestion in wireless communication system

ABSTRACT

Embodiments herein provide a wireless communication system for managing a network slice congestion. The wireless communication system includes a User Equipment (UE), operably coupled to a core network. The UE is configured to transmit a first NAS signaling message to the core network, wherein the first NAS signaling message comprises a specific network slide identity. The core network i configured to detect the network slice congestion in the wireless communication system. Further, the core network is configured to indicate the network slice congestion using a second NAS signaling message to the User Equipment (UE), wherein the second NAS signaling message comprising a reject cause value and a back off timer for the requested network slice identity.

TECHNICAL FIELD

The embodiment herein relates to a wireless communication system, andmore particularly relates to a User Equipment (UE) and core network formanaging network slice congestion in the wireless communication system.

BACKGROUND ART

To meet the demand for wireless data traffic having increased sincedeployment of 4th generation (4G) communication systems, efforts havebeen made to develop an improved 5th generation (5G) or pre-5Gcommunication system. The 5G or pre-5G communication system is alsocalled a ‘beyond 4G network’ or a ‘post long term evolution (LTE)system’. The 5G communication system is considered to be implemented inhigher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplishhigher data rates. To decrease propagation loss of the radio waves andincrease the transmission distance, beamforming, massive multiple-inputmultiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna,analog beamforming, and large scale antenna techniques are discussedwith respect to 5G communication systems. In addition, in 5Gcommunication systems, development for system network improvement isunder way based on advanced small cells, cloud radio access networks(RANs), ultra-dense networks, device-to-device (D2D) communication,wireless backhaul, moving network, cooperative communication,coordinated multi-points (CoMP), reception-end interference cancellationand the like. In the 5G system, hybrid frequency shift keying (FSK) andFeher's quadrature amplitude modulation (FQAM) and sliding windowsuperposition coding (SWSC) as an advanced coding modulation (ACM), andfilter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA),and sparse code multiple access (SCMA) as an advanced access technologyhave been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofeverything (IoE), which is a combination of the IoT technology and thebig data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “security technology” have been demanded forIoT implementation, a sensor network, a machine-to-machine (M2M)communication, machine type communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing information technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, MTC, and M2M communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RAN as theabove-described big data processing technology may also be considered tobe as an example of convergence between the 5G technology and the IoTtechnology.

As described above, various services can be provided according to thedevelopment of a wireless communication system, and thus a method foreasily providing such services is required.

DISCLOSURE Technical Solution

The principal object of the embodiments herein is to provide a UserEquipment (UE) and a core network for managing network slice congestionin a wireless communication system.

Another object of the embodiments herein is to indicate the networkslice congestion using a second NAS signaling message to the UserEquipment (UE), wherein the NAS signaling message comprising a rejectcause value and a back off timer for the requested network sliceidentity.

Another object of the embodiments herein is to perform a retransmissionof a first NAS signaling message, once the back off timer is expired.

Another object of the embodiments herein is to determine data pathcongestion on the PDU session IDs.

Another object of the embodiments herein is to indicate the data pathcongestion to the UE using the second NAS signaling message, wherein theNAS signaling message comprises a reject cause value and a back offtimer for the data plane congestion on the PDU session IDs.

Another object of the embodiments herein is to store the back off timerfor the data path congestion on the PDU session ID.

Another object of the embodiments herein is to transmit the servicerequest for user plane resources of the PDU session ID, to the corenetwork after an expiry of the back off timer associated with the PDUsession ID.

Another object of the embodiments herein is to provide a method andsystem for maintaining service continuity by the User Equipment (UE) inthe wireless communication system.

Another object of the embodiments herein is to detect a change inlocation during a mobility of the UE from a first radio accesstechnology to a second radio access technology.

Another object of the embodiments herein is to initiate an attachrequest procedure with other registered RAT information for maintainingthe service continuity.

Another object of the embodiments herein is to operate the UE in a dualregistration even a registration accept message indicates the UE tosupport the single registration.

DESCRIPTION OF DRAWINGS

The embodiments herein will be better understood from the followingdetailed description with reference to the drawings, in which:

FIG. 1a is a schematic diagram illustrating a method of detecting acongestion in a specific slice of a wireless communication system,according to a prior art;

FIG. 1b is a sequence diagram illustrating the method of detecting thecongestion in the specific slice of the wireless communication system,according to a prior art;

FIG. 2a is a schematic diagram illustrating a method of detecting anetwork slice congestion between a slice and a DNN, according to a priorart;

FIG. 2b is a sequence diagram illustrating the method of detecting thenetwork slice congestion between the slice and the DNN, according to aprior art;

FIG. 3a is a schematic diagram illustrating a method of detecting a datapath congestion between the slice and the DNN, according to a prior art;

FIG. 3b is a sequence diagram illustrating a method of detecting thedata path congestion between the slice and the DNN, according to a priorart;

FIG. 4 is a block diagram of the wireless communication system in whicha UE communicates with a core network for managing the network slicecongestion, according to an embodiment as disclosed herein;

FIG. 5a is a block diagram of a network slice congestion engine of thecore network for managing the network slice congestion, according to anembodiment as disclosed herein;

FIG. 5b is a block diagram of a network slice congestion engine of theUE for managing the network slice congestion, according to an embodimentas disclosed herein;

FIG. 6 is a flow diagram illustrating various operations for maintainingthe network slice congestion in the wireless communication system,according to an embodiment as disclosed herein;

FIG. 7 is a flow diagram illustrating various operations for maintaininga data path congestion in the wireless communication system, accordingto an embodiment as disclosed herein;

FIG. 8a is a sequence diagram illustrating a method of detecting acongestion in a specific slice of the wireless communication system,according to a prior art;

FIG. 8b is a sequence diagram illustrating a method of indicating thecongestion in the specific slice to the UE, according to an embodimentas disclosed herein;

FIG. 9a is a sequence diagram illustrating a method of detecting thenetwork slice congestion between the slice and the DNN, according to aprior art;

FIG. 9b is a sequence diagram illustrating a method of indicating thenetwork slice congestion between the slice and the DNN to the UE,according to an embodiment as disclosed herein;

FIG. 10a is a sequence diagram illustrating a method of detecting thedata path congestion between the slice and the DNN, according to a priorart;

FIG. 10b is a sequence diagram illustrating a method of indicating thedata path congestion between the slice and the DNN to the UE, accordingto an embodiment as disclosed herein;

FIG. 11a is a sequence diagram illustrating a method of receiving aregistration failure message (e.g., temporary rejection) from the MMEduring registration, according to a prior art;

FIG. 11b is a scenario of registration accept without indicating dualregistration, according to prior art;

FIG. 12 is an architecture diagram of a wireless communication system,according to an embodiment as disclosed herein;

FIG. 13 is a block diagram of the UE for handling dual registration inthe wireless communication system, according to an embodiment asdisclosed herein;

FIG. 14 is a block diagram of a service continuity controller of the UE,according to an embodiment as disclosed herein;

FIG. 15 is a flow diagram illustrating various operations formaintaining a service continuity by the UE in the wireless communicationsystem, according to an embodiment as disclosed herein;

FIG. 16a is a sequence diagram illustrating a method of receiving aregistration failure message (e.g., temporary rejection) from the MMEduring registration, according to a prior art;

FIG. 16b is a sequence diagram illustrating a method of maintaining theservice continuity by the UE in the wireless communication system,according to an embodiment as disclosed herein;

FIG. 17 is a flow diagram illustrating various operations for handlingdual registration by the UE in the wireless communication system,according to an embodiment as disclosed herein;

FIG. 18a is a scenario of registration accept without indicating dualregistration, according to prior art; and

FIG. 18b is a scenario of registration accept without indicating dualregistration, according to an embodiment as disclosed herein.

FIG. 19 is a block diagram illustrating the structure of a userequipment according to another embodiment of the present disclosure.

FIG. 20 is a block diagram illustrating the structure of a base stationaccording to another embodiment of the present disclosure.

BEST MODE

Accordingly the embodiments herein provide a wireless communicationsystem for managing network slice congestion. The wireless communicationsystem includes a User Equipment (UE), operably coupled to a corenetwork. The UE is configured to transmit a first NAS signaling messageto the core network, wherein the first NAS signaling message comprises aspecific network slice identity. The core network is configured todetect the network slice congestion in the wireless communicationsystem. Further, the core network is configured to indicate the networkslice congestion using a second NAS signaling message to the UserEquipment (UE), wherein the second NAS signaling message comprising areject cause value and a back off timer for the requested network sliceidentity.

In an embodiment, further the UE is configured to receive the second NASsignaling message comprising the reject cause value and the back offtimer for the requested network slice identity, in response to detectingthe network slice congestion. Further, the UE is configured to perform aretransmission of first NAS signaling message, once the back off timeris expired.

In an embodiment, the network slice congestion is detected on one of thespecific network slice in the wireless communication system OR, on anetwork slice and a Data Network Name (DNN) combination of the wirelesscommunication system.

In an embodiment, the UE is configured to avoid retransmission of thefirst NAS signaling message for the specific network slice identityuntil an expiry of the back off timer.

In an embodiment, the UE is configured to avoid retransmission of thefirst NAS signaling message for the specific network slice identity andthe DNN combination until an expiry of the back off timer.

Accordingly the embodiments herein provide a wireless communicationsystem for managing network slice congestion. The wireless communicationsystem includes a User Equipment (UE), operably coupled to a corenetwork. The UE is configured to transmit a service request to the corenetwork through a first NAS signaling message, wherein the servicerequest comprises Protocol Data Unit (PDU) session ID. The core networkis configured to receive a service request from the UE through the firstNAS signaling message, wherein the service request comprises a ProtocolData Unit (PDU) session IDs. Further, the core network is configured todetermine a data path congestion on the PDU session IDs. Further, thecore network is configured to indicate the data path congestion to theUE using the second NAS signaling message, wherein the second NASsignaling message comprises a reject cause value and a back off timerfor the data plane congestion on the PDU session IDs.

In an embodiment, the UE is configured to receive the second NASsignaling message from the core network, wherein the second NASsignaling message comprises a reject cause value and the back off timerfor the data plane congestion on the PDU session ID, in response todetecting the network slice congestion. Further, the UE is configured tostore the back off timer for the data path congestion on the PDU sessionID. Further, the UE is configured to avoid transmitting the servicerequest for user plane resources of the PDU session ID, to the corenetwork until an expiry of the back off timer associated with the PDUsession ID.

Accordingly the embodiments herein provide a core network for managingnetwork slice congestion in a wireless communication system. The corenetwork includes a network slice congestion engine, operably coupledwith a memory and a processor. The network slice congestion engine isconfigured to detect the network slice congestion in the wirelesscommunication system, upon receiving a service request from the UserEquipment (UE) through a first NAS signaling message comprises aspecific network slide identity. Further, the network slice congestionengine is configured to indicate the network slice congestion using asecond NAS signaling message to the UE, wherein the second NAS signalingmessage comprising a reject cause value and a back off timer for therequested network slice identity.

Accordingly the embodiments herein provide a UE for managing a networkslice congestion in a wireless communication system. The UE includes anetwork slice congestion engine, operably coupled with a memory and aprocessor. The network slice congestion engine is configured to transmita first NAS signaling message to the core network, wherein the first NASsignaling message comprises a specific network slide identity. Further,the network slice congestion engine is configured to receive a secondNAS signaling message from the core network, wherein the second NASsignaling message comprising the reject cause value and the back offtimer for the requested network slice identity, upon detecting thenetwork slice congestion. Further, the network slice congestion engineis configured to perform a retransmission of the service request throughthe first NAS signaling message, once the back off timer expired.

In an embodiment, the network slice congestion engine is furtherconfigured to avoid retransmission of the first NAS signaling messagefor the specific network slice identity until an expiry of the back offtimer.

In an embodiment, the network slice congestion engine is furtherconfigured to avoid retransmission of the first NAS signaling messagefor the combination of specific network slice identity and the DNN untilan expiry of the back off timer.

Accordingly the embodiments herein provide a core network for managing anetwork slice congestion in a wireless communication system. The corenetwork includes a network slice congestion engine, operably coupledwith a memory and a processor. The network slice congestion engine isconfigured to receive a service request from a User Equipment (UE)through a first NAS signaling message, wherein the service requestcomprises Protocol Data Unit (PDU) session IDs. Further, the networkslice congestion engine is configured to determine a data pathcongestion on the PDU session IDs. Furthermore, the network slicecongestion engine is configured to indicate the data path congestion tothe UE using the second NAS signaling message, wherein the second NASsignaling message comprises a reject cause value and a back off timerfor the data plane congestion on the PDU session IDs.

Accordingly the embodiments herein provide a UE for managing a networkslice congestion in a wireless communication system. The UE includes anetwork slice congestion engine, operably coupled with a memory and aprocessor. The network slice congestion engine is configured to transmita service request to the core network through a first NAS signalingmessage, wherein the service request comprises Protocol Data Unit (PDU)session IDs. Further, the network slice congestion engine is configuredto receive the second NAS signaling message from the core network,wherein the second NAS signaling message comprises the reject causevalue and the back off timer for the data plane congestion on the PDUsession ID, in response to detecting the network slice congestion.Further, the network slice congestion engine is configured to store theback off timer for the data path congestion on the PDU session ID.Furthermore, the network slice congestion engine is configured to avoidtransmitting the service request for the user plane resources of the PDUsession ID to the core network until an expiry of the back off timerassociated with the PDU session ID.

Accordingly the embodiments herein provide a method for managing anetwork slice congestion in a wireless communication system by a corenetwork. The method includes detecting, by the core network, the networkslice congestion in the wireless communication system, upon receiving aservice request from the User Equipment (UE) through a first NASsignaling message comprises a specific network slide identity. Further,the method includes indicating, by the core network, the network slicecongestion using a second NAS signaling message to the UE, wherein thesecond NAS signaling message comprising a reject cause value and a backoff timer for the specific network slice identity.

In an embodiment, wherein the network slice congestion is detected onone of the specific network slice in the wireless communication systemor, on a combination of network slice and a Data Network Name (DNN) ofthe wireless communication system.

Accordingly the embodiments herein provide a method for managing anetwork slice congestion in a wireless communication system a UserEquipment (UE). The method includes transmitting, by the UE, a first NASsignaling message to a core network, wherein the first NAS signalingmessage comprises a specific network slide identity. Further, the methodincludes receiving, by the UE, a second NAS signaling message from thecore network, wherein the second NAS signaling message comprising areject cause value and a back off timer for the specific network sliceidentity, upon detecting the network slice congestion. Furthermore, themethod includes performing, by the UE, a retransmission of the servicerequest through the first NAS signaling message, once the back off timerexpired.

Accordingly the embodiments herein provide a method for managing anetwork slice congestion in a wireless communication system by a corenetwork. The method includes receiving, by the core network, a servicerequest from a User Equipment (UE) through a first NAS signalingmessage, wherein the service request comprises Protocol Data Unit (PDU)session IDs. Further, the method includes determining, by the corenetwork, a data path congestion on the PDU session IDs. Furthermore, themethod includes indicating, by the core network, the data pathcongestion to the UE using a second NAS signaling message, wherein thesecond NAS signaling message comprises a reject cause value and a backoff timer for the data plane congestion on the PDU session IDs.

Accordingly the embodiments herein provide a method for managing anetwork slice congestion in a wireless communication system a UserEquipment (UE). The method includes transmitting, by the UE, a servicerequest to the core network through a first NAS signaling message,wherein the service request comprises Protocol Data Unit (PDU) sessionIDs. Further, the method includes receiving, by the UE, a second NASsignaling message from the core network, wherein the second NASsignaling message comprises a reject cause value and a back off timerfor the data plane congestion on the PDU session ID, in response todetecting the network slice congestion. Further, the method includesstoring, by the UE, the back off timer for the data path congestion onthe PDU session ID. Furthermore, the method includes transmitting, bythe UE, the service request for user plane resources of the PDU sessionID, to the core network after an expiry of the back off timer associatedwith the PDU session ID.

Accordingly the embodiments herein provide a method for maintaining aservice continuity by a User Equipment (UE) in a wireless communicationsystem. The method includes detecting, by the UE, a change in locationduring a mobility of the UE from a first registration or tracking areato another registration or tracking area within a first Radio AccessTechnology, wherein the UE is registered in core networks of twodifferent radio access technology (Dual Registration). Further, themethod includes triggering, by the UE, a tracking area update or amobility registration procedure in the first Radio Access Technology, inresponse to receiving a registration reject or tracking area updatereject from the core network on the first radio access technology.Furthermore, the method includes initiating, by the UE, an attachrequest or registration request procedure by transmitting an attachrequest or initial registration request message in response to receivingthe receiving the registration reject or tracking area update reject,wherein the initial attach request or initial registration requestmessage comprising a registration status of the UE of a second Radioaccess technology to a core network of the first Radio Access Technology(RAT).

In an embodiment, the first radio access technology and second radioaccess technology include at least one of a 3rd Generation PartnershipProject (3GPP) Long Term Evolution (LTE) RAT and a 3GPP New Radio (NR)RAT.

In an embodiment, the registered status of the second Radio AccessTechnology (RAT) comprises of the UE status IE which indicates if UE isregistered with 4G network (with indication of UE is in EMM-REGISTEREDstate) or not registered with 4G network (with indication of UE is notin EMM-REGISTERED state) when the UE is registering with AMF. If the UEregistering with MME the other registered RAT registration statuscomprises of the UE status IE which indicates if UE is registered with5G network (with indication of UE is in 5GMM-REGISTERED state) or notregistered with 5G network (with indication of UE is not in5GMM-REGISTERED state).

In an embodiment, the service continuity to the UE is maintained byretaining the other registered RAT information of the UE at the CoreNetwork associated with the second radio access technology.

Accordingly the embodiments herein provide a method for handling dualregistration of a User Equipment (UE) in a wireless communicationsystem. The method includes determining that the UE supports dualregistration on different RATs when Nx (N26) interface is availablebetween AMF and MME. Further, the method includes receiving aregistration accept message from an Access and Mobility ManagementFunction (AMF) entity, wherein the registration accept message indicatesthe UE to support a single registration. Furthermore, the methodincludes operating the UE in the dual registration even thoughregistration accept message indicates the UE to operate in the singleregistration mode.

Accordingly the embodiments herein provide a UE for maintaining aservice continuity in a wireless communication system. The UE includes aservice continuity controller operably coupled with a memory and aprocessor. The service continuity controller is configured to detect achange in location during a mobility of the UE from a first registrationor tracking area to another registration or tracking area within a firstRadio Access Technology, wherein the UE is registered in core networksof two different radio access technology (Dual Registration). Theservice continuity controller is configured to trigger a tracking areaupdate or a mobility registration procedure in the first Radio AccessTechnology, in response to receiving a registration reject or trackingarea update reject from the core network on the first radio accesstechnology. Further, the service continuity controller is configured toinitiate an attach request or registration request procedure bytransmitting an attach request or initial registration request messagein response to receiving the receiving the registration reject ortracking area update reject, wherein the initial attach request orinitial registration request message comprising a registration status ofthe UE of a second Radio access technology to a core network of thefirst Radio Access Technology (RAT).

In an embodiment, the registration status of the UE of the second Radioaccess technology comprises: Evolved Packet System (EPS) MobilityManagement (EMM) registration status set to one of: the UE is not inEMM-REGISTERED state and the UE is in EMM-REGISTERED state, whenregistering to the Access and Mobility Management Function (AMF), or5GMM registration status set to one of: the UE is not in 5GMM-REGISTEREDstate and UE is in 5GMM-REGISTERED state, when registering to theMobility Management Function (MME).

Accordingly the embodiments herein provide a UE for handling dualregistration in a wireless communication system. The UE includes aregistration engine operably coupled with a memory and a processor. Theregistration engine is configured to determine that the UE supports dualregistration on different RATs when Nx (N26) interface is available.Further, the registration engine is configured to receive a registrationaccept message from an Access and Mobility Management Function (AMF)entity, wherein the registration accept message indicates the UE tooperate in a single registration mode. Furthermore, the registrationengine is configured to operate the UE in the dual registration modeeven though registration accept message indicates the UE to operate inthe single registration mode.

These and other aspects of the embodiments herein will be betterappreciated and understood when considered in conjunction with thefollowing description and the accompanying drawings. It should beunderstood, however, that the following descriptions, while indicatingpreferred embodiments and numerous specific details thereof, are givenby way of illustration and not of limitation. Many changes andmodifications may be made within the scope of the embodiments hereinwithout departing from the spirit thereof, and the embodiments hereininclude all such modifications.

MODE FOR INVENTION

The embodiments herein and the various features and advantageous detailsthereof are explained more fully with reference to the non-limitingembodiments that are illustrated in the accompanying drawings anddetailed in the following description. Descriptions of well-knowncomponents and processing techniques are omitted so as to notunnecessarily obscure the embodiments herein. Also, the variousembodiments described herein are not necessarily mutually exclusive, assome embodiments can be combined with one or more other embodiments toform new embodiments. The term “or” as used herein, refers to anon-exclusive or, unless otherwise indicated. The examples used hereinare intended merely to facilitate an understanding of ways in which theembodiments herein can be practiced and to further enable those skilledin the art to practice the embodiments herein. Accordingly, the examplesshould not be construed as limiting the scope of the embodiments herein.

As traditional in the field, embodiments may be described andillustrated in terms of blocks which carry out a described function orfunctions. These blocks, which may be referred to herein as units ormodules or the like, are physically implemented by analog and/or digitalcircuits such as logic gates, integrated circuits, microprocessors,microcontrollers, storage circuits, passive electronic components,active electronic components, optical components, hardwired circuits andthe like, and may optionally be driven by firmware and/or software. Thecircuits may, for example, be embodied in one or more semiconductorchips, or on substrate supports such as printed circuit boards and thelike. The circuits constituting a block may be implemented by dedicatedhardware, or by a processor (e.g., one or more programmedmicroprocessors and associated circuitry), or by a combination ofdedicated hardware to perform some functions of the block and aprocessor to perform other functions of the block. Each block of theembodiments may be physically separated into two or more interacting anddiscrete blocks without departing from the scope of the disclosure.Likewise, the blocks of the embodiments may be physically combined intomore complex blocks without departing from the scope of the disclosure.

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, or the like. In order to achieve a high datatransmission rate, 5G communication system is considered to beimplemented in a millimeter wave (mm Wave) or extremely higher frequencybands as well, for e.g., 28 GHz, 60 GHz, etc., so as to accomplishhigher data rates. In conventional systems, different services use acorresponding number of dedicated communication networks, each tailoredto the respective service to be implemented. Instead of using aplurality of specifically designed networks, another approach, known asnetwork slicing, may use a single network architecture, allows multiplevirtual networks to be created on top of a common shared physicalinfrastructure. In the case of 5G, a single physical network will besliced into multiple virtual networks that can support different radioaccess networks (RANs), or different service types running across asingle RAN.

FIG. 1a is a schematic diagram illustrating a method of detecting acongestion in a specific slice of a wireless communication system,according to a prior art. In the 5G system, a User Equipment (UE) canconnect to a same Data Network Name (DNN) using multiple slices. Theslice has its own network resources to provide a specific service to theUE. As shown in the FIG. 1a , there is possibility that the DNN is notcongested but only a particular network slice is overloaded. FIG. 1b isa sequence diagram illustrating a method of detecting a slice congestionin the wireless communication system, according to a prior art. However,as shown in the FIG. 1b , there is no method for defining the networkslice congestion, and there is no possibility for the network toindicate the UE about the network slice congestion. Hence, the UE keepsretransmitting a service request for the specific slice. This result ina radio resource wastage and un-necessary signaling from the UE cancause increase in power consumption.

FIG. 2a is a schematic diagram illustrating a method of detecting anetwork slice congestion between a slice and a DNN, according to a priorart. The UE can connect to different DNNs using same slice ID. Further,there is possibility that only one particular DNN and slice pair iscongested which can happen if there are too many Protocol Data Units(PDUs) on the network side using same DNN and slice. FIG. 2b is asequence diagram illustrating a method of detecting a network slicecongestion between a slice and a DNN, according to a prior art. Forexample, as shown in the FIG. 2b , DNN1+slice2 is congested andDNN2+slice2 are not. However, there is no method to indicate that aparticular “DNN+Slice” pair is congested to the UE.

FIG. 3a is a schematic diagram illustrating a method of detecting a datapath congestion between the slice and the DNN, according to a prior art.FIG. 3b is a sequence diagram illustrating a method of detecting a datapath congestion between the slice and the DNN, according to a prior art.For example, as shown in the FIG. 3b , data path is congested. However,there is no method in which the network can indicate the UE that thedata path is congested. Hence, the UE keeps retransmitting the PDUs,even the data path is congested in the network.

Further, the wireless communication systems are widely deployed toprovide various types of communication content such as voice, video,packet data, messaging, broadcast, or the like. In the wirelesscommunication system, for a dual-mode or a multi-mode registration, aUser Equipment (UE) includes dual or multiple radio transceivers, eachconfigured to communicate on a particular radio access technology (RAT),such as 3^(rd) Generation Partnership Project (3GPP) access systems suchas 4G system and 5G system and non-3GPP access systems. However, incurrent systems, UE can maintain some PDN's in 4G RAT and some PDU's in5G RAT. Further, during location change of the UE during mobility fromone tracking area to another tracking area in active RAT (4G or 5G), UEinitiates tracking area update or registration request procedure. Insuch scenario, if UE receives the temporary network reject from thenetwork, Initial Attach Request or Initial Registration request isinitiated by the UE in active RAT, which triggers core network of theactive RAT to initiate location update to the HS S/UDM. Due to thislocation update procedure to HSS/UDM, PDU's active for UE on alternateRAT's are deactivated causing data loss for the UE.

FIG. 11a is a sequence diagram illustrating a method of receiving aregistration failure message (e.g., temporary rejection) from the MMEduring registration, according to a prior art. As shown in the FIG. 1a ,consider another scenario that the UE 100 is registered in the dual-moderegistration, in which the UE 100 can access the 3GPP access network(such as 4G) using an old MME 310 a. If the UE 100 moves to a newtracking area within a 4G coverage area then, the UE 100 detects changesin the tracking area at UE at step 101. Further, at step 102, the UE 100can send a Tracking Area update (TAU) attach request with a new MME 310b. However, the new MME 310 b can send a tracking area reject/implicitdetach to the UE 100 at step 103. As the 4G identity is still valid, theUE 100 may send an attach request with a native 4G GUTI details to thenew MME 310 b at step 104. As the UE 100 does not includes that the oldMME 310 a as the AMF 320 in the attach request, the new MME 310 b maysend the update location to Home Subscriber Server/User Data Model(HSS/UDM) 330 with an initial attach flag set at step 105. Further, theHSS/UDM 330 can delete the entire context from the UE 100 by sendingcancel location to the AMF 320, even the PDU in the 5G RAT networkremains active at step 106. This results in a loss of connection due toswitching from one tracking area to another tracking area.

Currently, dual registration is given by the network in the 5G inregistration accept if the N26 interface is not supported by thenetwork. However, there can be some devices which support dual radiowhich may want to use the dual registration to support different PDU ondifferent RAT. Current Standard doesn't provide the provision for the UE100 to take the decision whether it wants to support the dualregistration over single registration even if N26 interface is there.

As shown in the FIG. 11b , the UE 100 sends the registration request tothe AMF 320. If N26 interface is there and the AMF 320 sends theregistration accept without indicating dual registration to the UE 100and the UE 100 is mandated to follow single mode procedures.

Thus, it is desired to address the above mentioned disadvantages orother shortcomings or at least provide a useful alternative.

Accordingly the embodiments herein provide a wireless communicationsystem for managing a network slice congestion. The wirelesscommunication system includes a User Equipment (UE), operably coupled toa core network. The UE is configured to transmit a first NAS signalingmessage to the core network, wherein the first NAS signaling messagecomprises a specific network slide identity. The core network isconfigured to detect the network slice congestion in the wirelesscommunication system. Further, the core network is configured toindicate the network slice congestion using a second NAS signalingmessage to the User Equipment (UE), wherein the second NAS signalingmessage comprising a reject cause value and a back off timer for therequested network slice identity.

Unlike conventional methods and systems, the proposed method can be usedto indicate the UE, that one of a specific slice is congested; thespecific slice and the DNN combination are congested. Further, the UEstops transmitting signaling message to the core network for a back offtimer. This results in saving radio resources and does not overload thecore network. Hence, this results in power saving of the UE.

The proposed method can be used to indicate that the data path iscongested between the specific slice and the DNN to the UE. Hence, thisavoids unnecessary signaling to the core network for data bearer setupand thus saves power at the UE.

Embodiments herein provide a method for maintaining a service continuityby a User Equipment (UE) in a wireless communication system. The methodincludes detecting, by the UE, a change in location during mobility ofthe UE from a first radio access technology to a second radio accesstechnology. Further, the method includes initiating, by the UE, anattach request procedure in response to receiving the receiving theregistration reject or tracking area update reject, wherein the UE sendsan attach request message includes other registered RAT information to aMobility Management Entity (MME) associated with the second radio accesstechnology.

Unlike conventional methods and systems, the proposed method can be usedto avoid data loss in a dual registration mode of the UE. The proposedmethod allows the UE to send an attach request, where the attach requestincludes that the UE is registered on a RAT (e.g., 4G 3GPP) and analternate RAT (e.g., 5G non-3GPP). Thus the proposed method preventscancellation of the context information of the alternate RAT, when theUE switched from one tracking area to another tracking area in the givenRAT.

In conventional methods, the UE sends the registration request to anAMF. If N26 interface is there and the AMF sends the registration acceptwithout indicating dual registration to the UE and the UE is mandated tofollow single mode procedures.

Unlike to conventional method, the proposed method can be used to allowthe UE to obviate mandated the use of single registration when the dualregistration is not indicated to the UE. Further, the dual registrationcan be used with the dual radio case even when the single registrationis supported by the network.

Referring now to the drawings, and more particularly to FIG. 4 to FIG.7, FIG. 8b , FIG. 9b , FIG. 10b , FIG. 12 to FIG. 15, FIG. 16b to FIG.17, FIG. 18b , FIG. 19, and FIG. 20 there are shown preferredembodiments.

FIG. 4 is a block diagram of a wireless communication system 1000,according to an embodiment as disclosed herein. The wirelesscommunication system 1000 includes a core network 200 and a UE 100. Thecore network 200 can be a cellular network, for example a 3GPP Long TermEvolution (LTE) network such as an evolved universal terrestrial radioaccess technology (E-UTRAN), 4G, 5G. In another embodiment, the network400 may be a Wireless Local Area Network (WLAN) such as an Institute ofElectrical and Electronics Engineers (IEEE) 802.11 Wi-Fi network. In anembodiment, the core network 200 includes a network slice congestionengine 210, a communicator 220, a memory 230, and a processor 240.

The UE 100 communicates with the network 200 for providing one or moredata services to a user. In an example, the data service can be, forexample, voice communication, text messaging, multimedia streaming, andInternet access. The UE 100 can be, for e.g., a cellular telephone, asmart phone, a personal computer (PC), a minicomputer, a desktop, alaptop, a handheld computer, Personal Digital Assistant (PDA), or thelike. The UE 100 may support multiple Radio access technologies (RAT)such as, for e.g., Code-division multiple access (CDMA), General PacketRadio Service (GPRS), Evolution-Data Optimized EVDO (EvDO),Time-division multiple access (TDMA), GSM (Global System for MobileCommunications, WiMAX (Worldwide Interoperability for Microwave Access)technology, LTE, LTE Advanced and 5G communication technologies. In anembodiment, the UE 100 includes a network slice congestion engine 110, acommunicator 120, a memory 130, and a processor 140. The base station isa radio access network which allows the UE 100 to connect with the corenetwork 200.

The proposed method allows the core network 200 to indicate the slicecongestion and provide a specific reject cause to the UE 100. Further,the core network 200 provides back off timer for the specific slice.

In an embodiment, the network slice congestion engine 110 transmits afirst NAS signaling message to the core network 200. In an embodiment,the first NAS signaling message includes a specific network slideidentity.

In an embodiment, the network slice congestion engine 210 detects thenetwork slice congestion in the wireless communication system 1000 inresponse to receiving a service request from the UE 100 through thefirst NAS signaling message. In an embodiment, the network slicecongestion engine 210 detects the network slice congestion on thespecific network slice in the wireless communication system 1000. Inanother embodiment, the network slice congestion engine 210 detects thenetwork slice congestion on the network slice and a Data Network Name(DNN) combination of the wireless communication system 1000.

Further, the network slice congestion engine 210 indicates the networkslice congestion using a second NAS signaling message to the UE 100,wherein the second NAS signaling message includes a reject cause valueand a back off timer for the requested network slice identity.

In an embodiment, the network slice congestion engine 110 receives thesecond NAS signaling message includes the reject cause value and theback off timer for the specific network slice identity, in response todetecting the network slice congestion. Further, the network slicecongestion engine 110 performs a retransmission of the first NASsignaling message, once the back off timer is expired.

In an embodiment, the network slice congestion engine 110 avoidsretransmission of the first NAS signaling message for the specificnetwork slice identity until an expiry of the back off timer. In anembodiment, the network slice congestion engine 110 avoidsretransmission of the first NAS signaling message for the specificnetwork slice identity and the DNN combination until an expiry of theback off timer. Hence, this results in saving the network resources andpower consumption at the UE 100.

The proposed method can be used to detect the congestion happens for anentire DNN, or for a particular slice or for a particular Slice and DNNpair.

In another embodiment, the DNN/Slice level congestion control isapplicable only on Session Management (SM) signaling procedures. If theDNN congestion is active then the UE 100 shall not send another PDUsession establishment, modification request message for the sameDNN/slice. The DNN/slice-based session management congestion control isapplicable to the NAS SM signaling initiated from the UE in the ControlPlane. The Session Management congestion control does not prevent the UE100 to send and receive data or initiate the service request proceduresfor activating User Plane connection towards the DNN(s) that are underSession Management congestion control. The network slice congestionengine 110 transmits the service request to the core network 200 throughthe first NAS signaling message, where the service request includesProtocol Data Unit (PDU) session ID. In an embodiment, the network slicecongestion engine 210 receives the service request from the UE throughthe first NAS signaling message, where the service request includes aProtocol Data Unit (PDU) session IDs. Further, the network slicecongestion engine 210 determines a data path congestion on the PDUsession IDs in response to receiving the service request. Further, thenetwork slice congestion engine 210 indicates the data path congestionto the UE using the second NAS signaling message, wherein the second NASsignaling message includes a reject cause value and a back off timer forthe data plane congestion on the PDU session IDs.

In an embodiment, the network slice congestion engine 110 receives thesecond NAS signaling message from the core network 200, wherein thesecond NAS signaling message includes a reject cause value and the backoff timer for the data plane congestion on the PDU session ID, inresponse to detecting the network slice congestion. Further, the networkslice congestion engine 110 stores the back off timer for the data pathcongestion on the PDU session ID. Furthermore, the network slicecongestion engine 110 transmits the service request for user planeresources of the PDU session ID, to the core network after an expiry ofthe back off timer associated with the PDU session ID.

In an embodiment, the communicator 120 is configured to communicateinternally between hardware components in the core network 200. In anembodiment, the processor 140 is configured to process variousinstructions stored in the memory 130 for managing the network slicecongestion in the wireless communication system.

The memory 130 may include non-volatile storage elements. Examples ofsuch non-volatile storage elements may include magnetic hard discs,optical discs, floppy discs, flash memories, or forms of electricallyprogrammable memories (EPROM) or electrically erasable and programmable(EEPROM) memories. In addition, the memory 130 may, in some examples, beconsidered a non-transitory storage medium. The term “non-transitory”may indicate that the storage medium is not embodied in a carrier waveor a propagated signal. However, the term “non-transitory” should not beinterpreted that the memory 130 is non-movable. In some examples, thememory 130 can be configured to store larger amounts of information thanthe memory. In certain examples, a non-transitory storage medium maystore data that can, over time, change (e.g., in Random Access Memory(RAM) or cache).

In an embodiment, the communicator 220 is configured to communicateinternally between hardware components in the UE 100. In an embodiment,the processor 240 is configured to process various instructions storedin the memory 230 for managing the network slice congestion in thewireless communication system.

The memory 230 may include non-volatile storage elements. Examples ofsuch non-volatile storage elements may include magnetic hard discs,optical discs, floppy discs, flash memories, or forms of electricallyprogrammable memories (EPROM) or electrically erasable and programmable(EEPROM) memories. In addition, the memory 130 may, in some examples, beconsidered a non-transitory storage medium. The term “non-transitory”may indicate that the storage medium is not embodied in a carrier waveor a propagated signal. However, the term “non-transitory” should not beinterpreted that the memory 230 is non-movable. In some examples, thememory 230 can be configured to store larger amounts of information thanthe memory. In certain examples, a non-transitory storage medium maystore data that can, over time, change (e.g., in Random Access Memory(RAM) or cache).

Although the FIG. 4 shows various hardware components of the corenetwork 200 and the UE 100 but it is to be understood that otherembodiments are not limited thereon. In other embodiments, the corenetwork 200 and the UE 100 may include less or more number ofcomponents. Further, the labels or names of the components are used onlyfor illustrative purpose and does not limit the scope of the invention.One or more components can be combined together to perform same orsubstantially similar function of managing network slice congestion inthe wireless communication system 1000.

FIG. 5a is a block diagram of the network slice congestion engine 210 ofthe core network 200 for managing network slice congestion, according toan embodiment as disclosed herein. In an embodiment, the network slicecongestion engine 210 includes a network slice congestion detector 211,a network slice congestion indication controller 212, a data pathcongestion detector 213, and a data path congestion controller 214.

In an embodiment, the network slice congestion detector 111 detects thenetwork slice congestion in the wireless communication system 1000 inresponse to receiving the service request from the UE 100 through thefirst NAS signaling message. In an embodiment, the network slicecongestion detector 211 detects the network slice congestion on thespecific network slice in the wireless communication system 1000. Inanother embodiment, the network slice congestion detector 211 detectsthe network slice congestion on the network slice and a Data NetworkName (DNN) combination of the wireless communication system 1000.

Further, the network slice congestion indication controller 212indicates the network slice congestion using the second NAS signalingmessage to the UE 100, wherein the second NAS signaling message includesthe reject cause value and the back off timer for the requested networkslice identity.

In another embodiment, the data path congestion detector 113 determinesthe data path congestion on the PDU session IDs in response to receivingthe service request. Further, the data path congestion controller 214indicates the data path congestion to the UE 100 using the first NASsignaling message, where the first NAS signaling message includes areject cause value and a back off timer for the data plane congestion onthe PDU session IDs.

FIG. 5b is a block diagram of a network slice congestion engine of theUE 100 for managing network slice congestion, according to an embodimentas disclosed herein. In an embodiment, the network slice congestionengine 110 includes a network slice congestion controller 111 and a datapath congestion controller 112.

In an embodiment, the network slice congestion controller 111 transmitsthe service request to the core network 200 through the first NASsignaling message, where the service request includes Protocol Data Unit(PDU) session ID.

In an embodiment, the network slice congestion controller 111 receivesthe second NAS signaling message includes the reject cause value and theback off timer for the specific network slice identity, in response todetecting the network slice congestion. Further, the data pathcongestion controller 112 performs a retransmission of the first NASsignaling message, once the back off timer is expired.

In an embodiment, the data path congestion controller 112 avoidsretransmission of the first NAS signaling message for the specificnetwork slice identity until an expiry of the back off timer. In anembodiment, the data path congestion controller 112 avoidsretransmission of the first NAS signaling message for the specificnetwork slice identity and the DNN combination until an expiry of theback off timer.

In another embodiment, the network slice congestion controller 111receives the second NAS signaling message from the core network 200,wherein the second NAS signaling message includes the reject cause valueand the back off timer for the data plane congestion on the PDU sessionID, in response to detecting the network slice congestion. Further, thedata path congestion controller 112 stores the back off timer for thedata path congestion on the PDU session ID. Furthermore, the data pathcongestion controller 112 transmits the service request for user planeresources of the PDU session ID, to the core network 200 after an expiryof the back off timer associated with the PDU session ID.

FIG. 6 is a flow diagram 600 illustrating various operations formaintaining the network slice congestion in the wireless communicationsystem, according to an embodiment as disclosed herein.

At 610, the method includes transmitting, by the UE 100, the first NASsignaling message to the core network 200. In an embodiment, the methodallows the network slice congestion controller 111 to transmit the firstNAS signaling message to the core network 200.

At 620, the method includes detecting, by the core network 200, thenetwork slice congestion in the wireless communication system 1000. Inan embodiment, the method allows the network slice congestion detector111 to detect the network slice congestion in the wireless communicationsystem 1000.

At 630, the method includes indicating, by the core network 200, thenetwork slice congestion using the second NAS signaling message to theUser Equipment (UE) 100, wherein the second NAS signaling messageincludes the reject cause value and the back off timer for the requestednetwork slice identity. In an embodiment, the method allows the networkslice congestion indication controller 112 to indicate the network slicecongestion using the second NAS signaling message to the User Equipment(UE) 100.

At 640, the method includes receiving, by the UE 100, the second NASsignaling message includes the reject cause value and the back off timerfor the requested network slice identity, in response to detecting thenetwork slice congestion. In an embodiment, the method allows thenetwork slice congestion controller 111 to receive the second NASsignaling message includes the reject cause value and the back off timerfor the requested network slice identity, in response to detecting thenetwork slice congestion.

At 650, the method includes performing, by the UE 100, theretransmission of first NAS signaling message, once the back off timeris expired. In an embodiment, the method allows the network slicecongestion controller 111 to perform the retransmission of first NASsignaling message, once the back off timer is expired.

The various actions, acts, blocks, steps, or the like in the flowdiagram 600 may be performed in the order presented, in a differentorder or simultaneously. Further, in some embodiments, some of theactions, acts, blocks, steps, or the like may be omitted, added,modified, skipped, or the like without departing from the scope of theinvention.

FIG. 7 is a flow diagram 700 illustrating various operations formaintaining a data path congestion in the wireless communication system,according to an embodiment as disclosed herein.

At 710, the method includes transmitting, by the UE 100, the servicerequest to the core network 200 through the first NAS signaling message,wherein the service request comprises Protocol Data Unit (PDU) sessionID. In an embodiment, the method allows the network slice congestioncontroller 111 to transmit the service request to the core network 200through the first NAS signaling message.

At 720, the method includes receiving, by the core network 200, theservice request from the UE 100 through the first NAS signaling message,wherein the service request includes the Protocol Data Unit (PDU)session IDs. In an embodiment, the method allows the network slicecongestion indication controller 212 to receive the service request fromthe UE 100 through the first NAS signaling message.

At 730, the method includes indicating, by the core network 200, thenetwork slice congestion using the second NAS signaling message to theUser Equipment (UE) 100, wherein the second NAS signaling messageincludes the reject cause value and the back off timer for the requestednetwork slice identity. In an embodiment, the method allows the networkslice congestion indication controller 212 to indicate the network slicecongestion using the second NAS signaling message to the User Equipment(UE) 100.

At 740, the method includes indicating, by the core network 200, thedata path congestion to the UE 100 using the second NAS signalingmessage, where the second NAS signaling message includes the rejectcause value and the back off timer for the data plane congestion on thePDU session IDs. In an embodiment, the method allows the network slicecongestion indication controller 212 to indicate the data pathcongestion to the UE 100 using the second NAS signaling message, wherethe second NAS signaling message includes the reject cause value and theback off timer for the data plane congestion on the PDU session ID.

At 750, the method includes receiving, by the UE 100, the second NASsignaling message from the core network 200, wherein the second NASsignaling message comprises the reject cause value and the back offtimer for the data plane congestion on the PDU session ID, in responseto detecting the network slice congestion. In an embodiment, the methodallows the network slice congestion controller 111 to receive the secondNAS signaling message from the core network 200.

At 760, the method includes storing, by the UE 100, the back off timerfor the data path congestion on the PDU session ID. In an embodiment,the method allows the data path congestion controller 112 to store theback off timer for the data path congestion on the PDU session ID.

At 770, the method includes transmitting the service request for userplane resources of the PDU session ID, to the core network 200 after anexpiry of the back off timer associated with the PDU session ID. In anembodiment, the method allows the data path congestion controller 112 totransmit the service request for user plane resources of the PDU sessionID, to the core network 200 after an expiry of the back off timerassociated with the PDU session ID.

The various actions, acts, blocks, steps, or the like in the flowdiagram 700 may be performed in the order presented, in a differentorder or simultaneously. Further, in some embodiments, some of theactions, acts, blocks, steps, or the like may be omitted, added,modified, skipped, or the like without departing from the scope of theinvention.

FIG. 8b is a sequence diagram illustrating a method of indicating thecongestion in the specific slice to the UE, according to an embodimentas disclosed herein.

The core network 200 indicates the congestion in the specific slice tothe UE 100. The core network 200 is referred as 5G Core Network (5G CN),5G Core (5GC), NextGen CN (NG CN), NGC, and variations thereof may beused interchangeably throughout this disclosure. The core network 200includes a Mobility Management Entity (MME), an Access Mobility Function(AMF), a Session Management Function (SMF), and a Data Network name(DNN).

The MME is configured to support an interworking procedure of thewireless communication system 1000. The MME is configured to perform thesignaling and control functions to support access to the networkconnection of the UE 100, assignment of network resources, paging,tracking, roaming and handover or the like. The MME deals with thecontrol plane functions related to subscriber and session management.Further, the MME manages several base stations, and performs thesignaling for the selection of a conventional gateway for a handover toanother 2G/3G network. The MME handles the signaling related to mobilityand security for E-UTRAN access. The MME is responsible for the trackingand the paging of UE in idle-mode. The MME is the termination point ofthe Non-Access Stratum (NAS).

The AMF supports the following functions: termination of NAS signaling,NAS ciphering & integrity protection, registration management,Connection management, Mobility management, Access authentication andauthorization, and Security context management. The SMF provides sessionmanagement, it may be managed by different SMF for each session when theUE 100 having a large number of sessions.

As shown in the FIG. 8b , the UE 100 configured to transmit a servicerequest on slice 1 at step 801. At step 802, the UE 100 transmits PDUsession establishment request (Slice #1). In response to receiving theservice request, the SMF determines that the Slice #1 is congested atstep 803. Further, the AMF provides the reject cause and the back offtimer for the Slice #1 at step 804.

At step 805, the AMF indicates the reject cause and the back off timerfor the Slice #1 to the UE 100 using the PDU session establishmentreject message. In response to receiving the PDU session establishmentreject message from the core network 200, the UE 100 does not retransmitthe service request for the Slice #1 for back off timer at step 806.There is no signaling from the UE 100 for the back off timer, whichsaves radio resources and does not overload the core network 200.

At step 807, after an expiry of the back off timer, the UE 100 doesretransmit for Slice #1 service. At step 808, the UE 100 transmits PDUsession establishment request (Slice #1). As the congestion is resolvedat the Slice #1 of the core network 200, the AMF transmits the PDUsession establishment Accept at step 809.

FIG. 9b is a sequence diagram illustrating a method of indicating thenetwork slice congestion between the slice and the DNN to the UE 100,according to an embodiment as disclosed herein. The core network 200indicates the congestion in the specific slice to the UE 100.

As shown in the FIG. 9b , the UE 100 configured to transmit a servicerequest on Slice #2 and DNN #1 combination, at step 901. At step 902,the UE 100 transmits PDU session establishment request (Slice #2, DNN1).In response to receiving the service request, the DNN1 determines thatthere is congestion at step 903. Further, the AMF indicates the rejectcause and the back off timer for the Slice #2, DNN1 to the UE 100 usingthe PDU session establishment reject message at step 904. In response toreceiving the PDU session establishment reject message from the AMF, theUE 100 does not retransmit the service request for the Slice #2 and DNN1combination for back off timer at step 905. There is no signaling fromthe UE 100 for the back off timer, which saves radio resources and doesnot overload the core network 200. In the meantime, the UE 100 can tryfor service on Slice #2, DNN #2 combinations at step 906. At step 907,the UE 100 transmits PDU session establishment request (Slice #2, DNN2)to the core network 200. In response to receiving the service request,the AMF transmits the PDU session establishment Accept at step 908.

At step 909, after an expiry of the back off timer, the UE 100 doesretransmit for the (Slice #2, DNN1) combination. In response toreceiving the service request, the DNN2 determines that there iscongestion at step 910. At step 911, the UE 100 transmits PDU sessionestablishment request (Slice #2, DNN1) combination. As the congestion isresolved at the (Slice #2, DNN1) combination of the core network 200,the AMF transmits the PDU session establishment Accept at step 912.

FIG. 10b is a sequence diagram illustrating a method of indicating thedata path congestion between the slice and the DNN to the UE 100,according to an embodiment as disclosed herein. The core network 200indicates the congestion in the specific slice to the UE 100.

As shown in the FIG. 10b , the UE 100 configured to transmit a servicerequest, where the service request includes PDU session IDs, at step1001. In response to receiving the service request, the AMF determinesthat whether the DDN is congested for data at step 1002. Further, theAMF indicates that the DNN congestion for data along with reject causeand the back off timer at step 1003. In response to reject cause and theback off timer from the AMF, the UE 100 stores the back off timer forthe PDU session ID and does not trigger service request till back offtimer expires for that PDU session ID at step 1004.

Hence, the congestion has been defined for data plane resources. Thisresults in avoids unnecessary signaling to the core network 200 for databearer setup and thus saves power at the UE 100.

FIG. 12 is an architecture diagram of the wireless communication system1000, according to an embodiment as disclosed herein. The wirelesscommunication system 1000 includes a network 400, an Evolved Packet Core(EPC) 300, base station (200 a-200 c) and a UE 100. The network 400 canbe a cellular network, for example a 3GPP Long Term Evolution (LTE)network such as an evolved universal terrestrial radio access technology(E-UTRAN), 4G, 5G. In another embodiment, the network 400 may be aWireless Local Area Network (WLAN) such as an Institute of Electricaland Electronics Engineers (IEEE) 802.11 Wi-Fi network.

The UE 100 communicates with the network 400 for providing one or moredata services to a user. In an example, the data service can be, forexample, voice communication, text messaging, multimedia streaming, andInternet access. The UE 100 can be configured to access the network 400via any one of 3GPP access network and a non-3GPP access network. Thebase station (200 a-200 c, hereinafter referred as 200) is a radioaccess network which allows the UE 100 to connect with the network 400.The radio access network can be for example a 3GPP access network and anon-3GPP access network. The UE 100 can access the 3GPP access networkvia base station 200 a and 200 b. Likewise, the UE 100 can access thenon-3GPP access network via base station 200 c. The 3GPP access networkcan be for example an Evolved-Universal Mobile Telecommunications System(UMTS) Terrestrial Radio access technology (E-UTRAN). For the 3GPPaccess network, the access information is specified in 3GPPspecifications.

For non-3GPP, the access information were not specified in the 3GPPspecifications. These technologies includes e.g. WiMAX, cdma2000®, WLANor fixed networks. The non-3GPP access network can be for exampleInstitute for Electrical and Electronics Engineers (IEEE) 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 IX, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The EPC 300 is referred as core network in the wireless communicationsystem 1000. The EPC 300 may be referred to as 5G Core Network (5G CN),5G Core (5GC), NextGen CN (NG CN), NGC, and variations thereof may beused interchangeably throughout this disclosure. The EPC 300 includes aMME 310, an Access Mobility Function (AMF) 320 and a HSS/UDM 330.

The MME 310 is configured to support an interworking procedure of thewireless communication system 1000. The MME 310 is configured to performthe signaling and control functions to support access to the networkconnection of the UE 100, assignment of network resources, paging,tracking, roaming and handover or the like. The MME 310 deals with thecontrol plane functions related to subscriber and session management.Further, the MME manages a number of base stations, and performs thesignaling for the selection of a conventional gateway for a handover toanother 2G/3G network. The MME 310 handles the signaling related tomobility and security for E-UTRAN access. The MME 310 is responsible forthe tracking and the paging of UE in idle-mode. The MME 310 is thetermination point of the Non-Access Stratum (NAS).

The AMF 320 supports the following functions:

a. Termination of NAS signaling,

b. NAS ciphering & integrity protection,

c. Registration management,

d. Connection management,

e. Mobility management,

f. Access authentication and authorization, and

g. Security context management.

In an embodiment, the AMF 320 has part of the MME functionality from EPC300.

The HSS/UDM 330 is a database that contains all the user subscriptioninformation, including user identification information such asInternational Mobile Subscriber Identity (IMSI), Mobile Subscriber ISDNNumber (MSISDN), or mobile telephone number, and user profileinformation that includes service subscription states anduser-subscribed Quality of Service information. The HSS/UDM 330 mayprovide the authentication and security information for the UE 100.

In an embodiment, the UE 100 can access the network 400 using a singleregistration mode or a dual registration mode in the wirelesscommunication system 1000.

In the conventional methods, there is no mechanism for handling whatwill be the UE 100 and the network 400 behavior when PDN interworking isnot there between the 4G network and the 5G network. Also, what will bethe network behavior when say certain PDU are not supported in one RATis not described in the conventional methods. The UE behavior for thecase when network supports registration on one access and not on otheraccess.

Unlike conventional methods and systems, the proposed method indicatesthat there should be a field in a SIM card or network slice selectionpolicy file which should indicate the RAT where PDU is supported basedon interworking RAT could be 4G, 5G, Non-3GPP or their combination. Ifthe UE 100 doesn't have subscription for the registration to certainaccess, then the network 400 should give subscription based the rejectcause. The reject cause can include the access where the registration isallowed or not allowed. The reject cause can include only 3GPP Accessallowed, only Non-3GPP access allowed. This subscription informationshall also be maintained in the SIM card which can give information thaton which access subscription is there, only 3GPP access, only Non-3GPPaccess or both are allowed.

Further, if the UE 100 does not have subscription for the PDUs tocertain access, then the network 400 should give subscription-basedreject cause for PDN connectivity request reject cause can include theaccess where registration is allowed or not allowed. The reject causecan include, for e.g., only 3GPP access allowed, only non-3GPP accessallowed, or none are allowed. This subscription information for PDUsshall also be maintained in the SIM card which can give information thaton which access subscription is there, only 3GPP access, only non-3GPPaccess or both are allowed.

FIG. 13 is a block diagram of the UE 100, according to an embodiment asdisclosed herein. In an embodiment, the UE 100 includes a servicecontinuity controller 1310, a registration engine 1320, a communicator1330, a memory 1340, and a processor 1350.

In an embodiment, the service continuity controller 1310 detects achange in location during mobility from a first radio access network 200a to a second radio access network 200 b. In an embodiment, within thefirst radio access network 200 a, the UE 100 may move from one locationto another location which causes the UE to switch from one RAT toanother RAT in the first radio access network 200 a itself

In an embodiment, the service continuity controller 1310 initiates anattach request procedure to the MME 310 b. The service continuitycontroller 1310 sends an attach request message includes otherregistered RAT information to a Mobility Management Entity (MME) 310 bassociated with the second radio access network 200 b. The otherregistered RAT information includes one or more radio access technologysubscribed by the UE 100 for one or more services.

In an embodiment, the first radio access network 200 a and the secondradio access network 200 b includes at least one of a 3rd GenerationPartnership Project (3GPP) access network and a non-3GPP access network.The 3GPP access network is at least one of a Long-Term Evolution (LTE)network and a New Radio (NR) network.

In an embodiment, the service continuity controller 1310 maintains theservice continuity by retaining the other registered RAT information ofthe UE 100 associated with the second radio access network 200 b.

In an embodiment, the registration engine 120 is operably coupled withthe memory 1340 and the processor 1350. The registration engine 1320 isconfigured to determine that the UE 100 supports dual registration ondifferent RATs when Nx (N26) interface is available. Further, theregistration engine 1320 is configured to receive a registration acceptmessage from an Access and Mobility Management Function (AMF) entity,wherein the registration accept message indicates the UE 100 to supporta single registration. Furthermore, the registration engine 1320 isconfigured to operate the UE 100 in the dual registration even theregistration accept message indicates the UE 100 to support the singleregistration.

In an embodiment, the communicator 130 is configured to communicateinternally between hardware components in the UE 100. In an embodiment,the processor 150 is configured to process various instructions storedin the memory 140 for handling the service continuity in the wirelesscommunication system.

The memory 1340 may include non-volatile storage elements. Examples ofsuch non-volatile storage elements may include magnetic hard discs,optical discs, floppy discs, flash memories, or forms of electricallyprogrammable memories (EPROM) or electrically erasable and programmable(EEPROM) memories. In addition, the memory 140 may, in some examples, beconsidered a non-transitory storage medium. The term “non-transitory”may indicate that the storage medium is not embodied in a carrier waveor a propagated signal. However, the term “non-transitory” should not beinterpreted that the memory 140 is non-movable. In some examples, thememory 140 can be configured to store larger amounts of information thanthe memory. In certain examples, a non-transitory storage medium maystore data that can, over time, change (e.g., in Random Access Memory(RAM) or cache).

Although the FIG. 13 shows various hardware components of the UE 100,but it is to be understood that other embodiments are not limitedthereon. In other embodiments, the UE 100 may include less or morenumber of components. Further, the labels or names of the components areused only for illustrative purpose and does not limit the scope of theinvention. One or more components can be combined together to performsame or substantially similar function of maintaining the servicecontinuity in the wireless communication system.

FIG. 14 is a block diagram of the service continuity controller 1310 ofthe UE 100, according to an embodiment as disclosed herein. In anembodiment, the service continuity controller 1310 includes a locationdetection controller 1311 and an attach request initiation controller1312.

In an embodiment, the location detection controller 1311 is configuredto detect a change in the location during the mobility from the firstradio access network 200 a to the second radio access network 200 b.

In an embodiment, the attach request initiation controller 1312 isconfigured to initiate the attach request procedure to the MME 310 b.The service continuity controller 1310 sends an attach request messageincludes other registered RAT information to the Mobility ManagementEntity (MME) 310 b associated with the second radio access network 200b.

FIG. 15 is a flow diagram 1500 illustrating various operations formaintaining the service continuity by the UE 100 in the wirelesscommunication system 1000, according to an embodiment as disclosedherein.

At step 1502, the method includes detecting, by the UE 100, the changein location during mobility of the UE 100 from a first registration ortracking area to another registration or tracking area within a firstRadio Access Technology, wherein the UE 100 is registered in corenetworks of two different radio access technology (Dual Registration).In an embodiment, the method allows the location detection controller1311 to detect the change in location during a mobility of the UE 100from a first registration or tracking area to another registration ortracking area within a first Radio Access Technology, wherein the UE 100is registered in core networks of two different radio accesstechnologies (Dual Registration).

At step 1504, the method includes triggering, by the UE 100, a trackingarea update or a mobility registration procedure in the first RadioAccess Technology on detecting the change in the location. In anembodiment, the method allows the location detection controller 1311 totrigger the tracking area update or a mobility registration procedure inthe first Radio Access Technology on detecting the change in thelocation.

At step 1506, the method includes receiving the registration reject ortracking area update reject from the core network on the first radioaccess technology. In an embodiment, the method allows the locationdetection controller 1311 to receive the registration reject or trackingarea update reject from the core network on the first radio accesstechnology.

The method includes initiating, by the UE 100, an attach request orregistration request procedure by transmitting an attach request orinitial registration request message, wherein the initial attach requestor initial registration request message comprising a registration statusof the UE 100 of a second Radio access technology to a core network ofthe first Radio Access Technology (RAT). In an embodiment, the methodallows the attach request initiation controller 1312 to initiate anattach request or registration request procedure by transmitting anattach request or initial registration request message, wherein theinitial attach request or initial registration request messagecomprising a registration status of the UE of a second Radio accesstechnology to a core network of the first Radio Access Technology (RAT).

The various actions, acts, blocks, steps, or the like in the flowdiagram 1500 may be performed in the order presented, in a differentorder or simultaneously. Further, in some embodiments, some of theactions, acts, blocks, steps, or the like may be omitted, added,modified, skipped, or the like without departing from the scope of theinvention.

FIG. 16b is a sequence diagram illustrating a method of maintaining theservice continuity by the UE 100 in the wireless communication system1000, according to an embodiment as disclosed herein. As shown in theFIG. 16b , the UE 100 is registered in the dual-mode registration, inwhich the UE 100 can access the 3GPP access network (such as 5G) and thenon-3GPP access network (such as 5G WI-FI connection) using the old MME310 a. In an embodiment, if the UE 100 moves to a new tracking areawithin a 5G coverage area then, the UE 100 detects the change in thetracking area at step 610. In another embodiment, if the UE 100 moves tothe new tracking area within the 5G coverage area then, the UE 100 andmay receive a trigger of TAU at step 610. In response to the detection,the UE 100 sends a Tracking Area Request (TAR) attach request to a newMME 310 b at step 620.

Further, the new MME 310 b may send a tracking area reject/implicitdetach to the UE 100, in response to receiving the TAR attach request atstep 630. As the 5G identity of the UE 100 is still valid, the UE 100may send an attach request with a native 5G GUTI details to the new MME310 b at step 640. The attach request includes the Globally UniqueTemporary Identifier (GUTI) value associated with the old MME 310 a andanother registered RAT information. The UE 100 may update a location toHSS/UDM 330 by Registration Request or Attach Request through AMF/MME320 at step 650. Accordingly, the MME 310 b may update a new location ofthe UE 100 based on a user-related and subscriber-related informationfrom the HSS/UDM 330, as the UE 100 moves from one tracking area toanother tracking area.

In an embodiment, consider a scenario in which the UE 100 is registeredin dual-mode registration, in which the UE 100 can access the 3GPPaccess network (such as 4G) and the non-3GPP access network (such as 5GWI-FI connection) using the old MME 310 a. During initial registrationitself, the UE 100 is configured to indicate on a given RAT (for e.g.,4G) that the UE 100 is also registered on alternate RAT (for e.g., 5G)to the new MME 310 b. If the new MME 310 b receives the information thatthe UE 100 is registered in the 5G/non-3GPP (AMF) then, the new MME 310b may not include an initial attach indication towards the UDM/HSS 310.Further, the UDM/HSS 310 does not delete the PDUs of 5Gconnection/non-3GPP access network.

FIG. 17 is a flow diagram 1700 illustrating various operations forhandling dual registration by the UE 100 in the wireless communicationsystem 1000, according to an embodiment as disclosed herein.

At 1710, the method includes determining that the UE 100 supports dualregistration on different RATs when Nx (N26) interface is available. Inan embodiment, the method allows registration engine 120 to determinethat the UE 100 supports dual registration on different RATs when Nx(N26) interface is available.

At 1720, the method includes receiving the registration accept messagefrom an Access and Mobility Management Function (AMF) entity, where theregistration accept message indicates the UE to support the singleregistration. In an embodiment, the method allows registration engine120 to receive the registration accept message from an Access andMobility Management Function (AMF) entity, where the registration acceptmessage indicates the UE to support the single registration.

At 1730, the method includes operating the UE 100 in the dualregistration in response to receiving the registration accept messageindicating the UE to support the single registration. In an embodiment,the method allows registration engine 120 to operate the UE 100 in thedual registration in response to receiving the registration acceptmessage indicating the UE to support the single registration.

FIG. 18a is a scenario of registration accept without indicating dualregistration, according to prior art.

As shown in the FIG. 18a , the UE 100 sends the registration request tothe AMF 320. If N26 interface is there and the AMF 320 sends theregistration accept without indicating dual registration to the UE 100and the UE 100 is mandated to follow single mode procedures.

FIG. 18b is a scenario of registration accepts without indicating dualregistration, according to an embodiment as disclosed herein.

As shown in the FIG. 18b , at 1, the UE 100 sends the registrationrequest to the AMF 320. If N26 interface is there and the AMF 320 sendsthe registration accept without indicating dual registration to the UE100. Further, the registration engine 120 allows the UE 100 to obviatemandated the use of single registration when the dual registration isnot indicated to the UE 100. Further, the dual registration can be usedwith the dual radio case even when the single registration is supportedby the network.

FIG. 19 is a block diagram illustrating the structure of a userequipment according to another embodiment of the present disclosure.

Referring to the FIG. 19, the user equipment 1900 may include aprocessor 1910, a transceiver 1920 and a memory 1930. However, all ofthe illustrated components are not essential. The user equipment 1900may be implemented by more or less components than those illustrated inFIG. 19. In addition, the processor 1910 and the transceiver 1920 andthe memory 1930 may be implemented as a single chip according to anotherembodiment. The processor 1910 may correspond to a Processor 150 of FIG.13. The transceiver 1920 may correspond to a Communicator 130 of FIG. 3.The memory 1930 may correspond to Memory 140.

The aforementioned components will now be described in detail.

The processor 1910 may include one or more processors or otherprocessing devices that control the proposed function, process, and/ormethod. Operation of the user equipment 1900 may be implemented by theprocessor 1910.

The processor 1910 may sense each configured resource pool and/or eachgroup of resources to obtain a result of sensing, the result of sensingcontaining a set of remaining candidate single TU resources of eachresource pool. The processor 910 may select, from the set of remainingcandidate single TU resources of each resource pool and/or each group ofresources, one candidate single TU resource as a transmission resource.

The transceiver 1920 may include a RF transmitter for up-converting andamplifying a transmitted signal, and a RF receiver for down-converting afrequency of a received signal. However, according to anotherembodiment, the transceiver 920 may be implemented by more or lesscomponents than those illustrated in components.

The transceiver 1920 may be connected to the processor 1910 and transmitand/or receive a signal. The signal may include control information anddata. In addition, the transceiver 1920 may receive the signal through awireless channel and output the signal to the processor 1910. Thetransceiver 1920 may transmit a signal output from the processor 1910through the wireless channel

The memory 1930 may store the control information or the data includedin a signal obtained by the device 900. The memory 1930 may be connectedto the processor 1910 and store at least one instruction or a protocolor a parameter for the proposed function, process, and/or method. Thememory 1930 may include read-only memory (ROM) and/or random accessmemory (RAM) and/or hard disk and/or CD-ROM and/or DVD and/or otherstorage devices.

FIG. 20 is a block diagram illustrating the structure of a base stationaccording to another embodiment of the present disclosure.

Referring to the FIG. 20, the base station 2000 may include a processor2010, a transceiver 2020 and a memory 2030. However, all of theillustrated components are not essential. The base station 2000 may beimplemented by more or less components than those illustrated in FIG.10. In addition, the processor 2010 and the transceiver 2020 and thememory 2030 may be implemented as a single chip according to anotherembodiment.

The aforementioned components will now be described in detail.

The processor 2010 may include one or more processors or otherprocessing devices that control the proposed function, process, and/ormethod. Operation of the base station 2000 may be implemented by theprocessor 2010.

The processor 2010 may determine the locations of transmission resourcesand reception resources.

The transceiver 2020 may include a RF transmitter for up-converting andamplifying a transmitted signal, and a RF receiver for down-converting afrequency of a received signal. However, according to anotherembodiment, the transceiver 2020 may be implemented by more or lesscomponents than those illustrated in components.

The transceiver 2020 may be connected to the processor 210 and transmitand/or receive a signal. The signal may include control information anddata. In addition, the transceiver 2020 may receive the signal through awireless channel and output the signal to the processor 2010. Thetransceiver 2020 may transmit a signal output from the processor 210through the wireless channel

The memory 2030 may store the control information or the data includedin a signal obtained by the device 2000. The memory 2030 may beconnected to the processor 2010 and store at least one instruction or aprotocol or a parameter for the proposed function, process, and/ormethod. The memory 2030 may include read-only memory (ROM) and/or randomaccess memory (RAM) and/or hard disk and/or CD-ROM and/or DVD and/orother storage devices.

The embodiments disclosed herein can be implemented through at least onesoftware program running on at least one hardware device and performingnetwork management functions to control the elements. The elements shownin the FIG. 4 to FIG. 7, FIG. 8b , FIG. 9b , FIG. 10b , FIG. 12 to FIG.15, FIG. 16b to FIG. 17, FIG. 18b , FIG. 19, and FIG. 20 include blockswhich can be at least one of a hardware device, or a combination ofhardware device and software module.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the embodiments herein that others can, byapplying current knowledge, readily modify or adapt for variousapplications such specific embodiments without departing from thegeneric concept, and, therefore, such adaptations and modificationsshould and are intended to be comprehended within the meaning and rangeof equivalents of the disclosed embodiments. It is to be understood thatthe phraseology or terminology employed herein is for the purpose ofdescription and not of limitation. Therefore, while the embodimentsherein have been described in terms of preferred embodiments, thoseskilled in the art will recognize that the embodiments herein can bepracticed with modification within the spirit and scope of theembodiments as described herein.

1-15. (canceled)
 16. A method, performed by a user equipment (UE), ofcontrolling network slice congestion, the method comprising:transmitting a service request message comprising at least one protocoldata unit (PDU) session ID; receiving a reject message comprisinginformation on a back-off timer when congestion for a network slice isdetected based on the at least one PDU session ID; and determiningwhether to perform a session management procedure based on the rejectmessage.
 17. The method of claim 16, wherein the back-off timer isassociated with the network slice, or a combination of the network sliceand a data network name (DNN).
 18. The method of claim 17, wherein thedetermining of whether to perform the session management procedurecomprises determining not to transmit message for the network slice, orthe combination of the network slice and the DNN, until the timerexpires.
 19. The method of claim 17, wherein the reject message is aNon-Access Stratum (NAS) signaling message and further comprises atleast one cause associated with rejecting a PDU session corresponding tothe PDU session ID.
 20. The method of claim 19, wherein the causecomprises information on insufficient user plane resources for the PDUsession.
 21. The method of claim 17, wherein the service request messageis not triggered until the back-off timer expires.
 22. The method ofclaim 19, further comprising transmitting a PDU session establishmentrequest message for the PDU session when the back-off timer expires. 23.A user equipment (UE), for controlling network slice congestion, the UEcomprising: a transceiver; and at least one processor coupled with thetransceiver and configured to: transmit a service request messagecomprising at least one protocol data unit (PDU) session ID, receive areject message comprising information on a back-off timer whencongestion for a network slice is detected based on the at least one PDUsession ID, and determine whether to perform a session managementprocedure based on the reject message.
 24. The UE of claim 23, whereinthe back-off timer is associated with the network slice, or acombination of the network slice and a data network name (DNN).
 25. TheUE of claim 24, wherein the at least one processor is further configuredto determine not to transmit message for the network slice, or thecombination of the network slice and the DNN, until the timer expires.26. The UE of claim 24, wherein the reject message is a Non-AccessStratum (NAS) signaling message and further comprises at least one causeassociated with rejecting a PDU session corresponding to the PDU sessionID.
 27. The UE of claim 26, wherein the cause comprises information oninsufficient user plane resources for the PDU session.
 28. The UE ofclaim 24, wherein the service request message is not triggered until theback-off timer expires.
 29. The UE of claim 26, wherein the at least oneprocessor is further configured to transmit a PDU session establishmentrequest message for the PDU session when the back-off timer expires.